My favorite divemaster in the Maldives, Manik Mohammed of the Manthiri live-aboard, has a great way of referring to the open ocean-he calls it "the Big Blue." So, late one night, when I asked if he and his crew would take me out to the Big Blue for a night dive, he knew just what I meant. I had dived with Manik and his guys the year before and they had been intrigued by my open ocean night dives. (I guess thinking someone is loony is akin to being intrigued.)

Manik got to be a little more than intrigued, however, because as divemaster, buddy and camera porter, he had to go, too. On this particular night, we went out off the reef about five miles, cut the engine, dropped a weighted line into the black water to about 100 feet and descended to the line's end. Manik's role was to carry my second camera, maintain contact with the line and keep a light on, giving me a visual reference so I wouldn't simply drift off on the brisk current while I peered into the dark through my camera.

In most places in the ocean-I've done this particular type of diving in The Bahamas, the Cayman Islands, Palau, the Seychelles and other areas-there is a rich, nighttime world of tiny animals. Most invertebrates and many fish spend the early portions of their lives as small embryos and larvae drifting about the ocean as part of a vast, planktonic soup that rises from deep water at night and descends during daylight hours. For a photographer, it's an amazing-and bizarre-world. Since most of the creatures are minuscule-less than the size of a pencil eraser-a Nikonos with a 1:1 extension tube (this means the image on the slide will be the same size as the actual animal) is a perfect set-up.

You slowly move your light back and forth through the water and look closely at the tiny specks that are illuminated. If something moves or appears to have color, you take its picture. Often, it's not until you get your film processed that you know what you've captured. Sometimes, you do see larger animals as well, such as shrimp, seawasps, squid and fish.

What makes this kind of diving even more interesting is that much of what you see and photograph is not identifiable, especially when you are far out at sea, diving deep. On that night in the Maldives, I photographed a strange invertebrate about an inch long that looked like a free-swimming tube anemone and withdrew its tentacles after my flash went off a few times; veliger stages of seashells, which have a tiny turn of shell at the top and long, extended tentacles; and most bizarre of all, a tiny, unidentified larva that looked like an eel with the head of a deep water Viperfish. Its beating heart and other organs were clearly visible through its transparent body and it had a huge (relatively speaking!) toothed jaw with barbels patterned in rows of luminous spots-obviously lures for dark water hunting-hanging down from its chin-a vicious predator less than an inch long!

Late one night in the Seychelles, some 12 miles out to sea from the remote island of Aldabra, we slipped into the dark water on snorkel. We were amazed to find ourselves surrounded by small, just hatched octopi, many thousands of them, that attached themselves to everything in reach-us, cameras, lights, whatever they could find. This area was particularly filled with life. I photographed an embryonic Cowfish; a tiny, one inch long butterflyfish; and most unusual, a one-half inch diameter jellyfish that had an equally sized fish living curled up in its bell.

But the Big Blue isn't just a place to see small creatures, the ocean's biggest animals live there as well, and if you are willing to invest a little time (chugging around in a boat, mainly), there are incredible marine life encounters possible. Besides the well-known commercially available trips, such as those to see the Sperm Whales off the Azores and Humpback Whales off the Dominican Republic, there are many lesser known opportunities as well.

In the Coral Sea, off Australia's Great Barrier Reef, the annual spawning season brings together gigantic congregations of fish. Far out at sea, massive schools of tuna pack tightly together into "fish balls" that also attract scores of open water predators. Andrew and Liz Wight, Australian filmmakers who have investigated this incredible phenomenon, describe electrifying dives in the midst of thousands upon thousands of churning, silvery tuna. As the fish roil and move in massive, sweeping waves, big Oceanic Whitetips, among the ocean's most aggressive sharks, sweep through, feeding voraciously until gorged.

But that's not all and such dives are not just reserved for the pros. Recently, divers on a Coral Sea live-aboard were astonished to see a huge, 800 pound Black Marlin surface behind the boat. They went in and the incredible, rare photographs that resulted are like few that have ever been taken.

Closer to home, those of us in Southern California have major adventure available in the Big Blue off our coastline. In an area called 15 Mile Bank, 15 miles out from Newport Beach, dives reveal Blue Sharks, White-sided Dolphins, sea lions and large, ungainly Mola mola (Ocean Sunfish) that drift about near the surface.

Farther south, off San Diego, proximity to warmer waters means a different collection of animals. One "secret" way to find many of them is to ride around in open ocean looking for floating mats of kelp (called kelp patties). When you find one, go in. Many animals seek the protection of the overhead cover; schooling Mackerel, the occasional Yellowtail Tuna and at times, Mahi mahi-aggressive to divers as they protect their prized patty, aglow in iridescent aggression colors, beautiful like few fish ever seen in the ocean.

My all-time most exciting dive is one of my California trips into that Big Blue. As reported in the 1997 Sharks and Divers Magazine, there was the day my buddy and I, drifting along at 30 feet some 15 miles offshore, were joined by a true denizen of the deep-a majestic 12 foot long Short Fin Mako that weighed, by all estimates, well more than 1,000 pounds. The 25 minutes she circled us as we hung suspended in the 1,600 foot deep open ocean remain as clear in my mind as though it were yesterday. It was an encounter I'll probably never experience again; an encounter few other people in the world have been so fortunate to have. And, like so many of open ocean diving's thrilling times, it was an event beyond the edge of what I could have imagined, a circumstance made all the more unique for its unlikely, extraordinary setting-there, deep in the cool, quiet heart of the Big Blue.